Can anyone tell me anything about these breakers?

[GoldDigger]

These are GE Magna blast that use puffers to aid extinguishing the arc. The have asbestos arc chutes with coils inside that set up a magnetic loop to oppose the arc. (Hence manga blast). The ones I worked on were used to start a 13.8 GE hydrogen synchronous condenser at Ontario Hydro in Toronto. I believe they were around 2000amp but my memory is vague. They are solenoid operated and ours were 250vdc. They rack in vertical buy cranking tool.
You could try contacting Hydro One surplus to see if they have any to sell.


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I take a bit of issue with the wording "oppose the arc". If I understand it correctly they do not so much oppose the arc (whatever that might mean) but force the arc to move away from the pole gap, increasing the arc distance faster than you could just by moving the pole pieces apart. The end result is that for DC the arc gets long enough that it can no longer be sustained or for AC the arc gets long enough that it cannot reignite after the zero crossing of the current.
AFAIK the magnetic field is created by coils, so that for AC it can always be of the correct polarity relative to the current direction so that the arc is always moved in the same direction.

 

[PaulMmn]

:lol: Good catch :happyyes:

For electrical equipment 50 years is old, for people- not really. Remember that the anticipated in service life is 40 years.

Is that service life for equipment or people??

 

[mbrooke]

I take a bit of issue with the wording "oppose the arc". If I understand it correctly they do not so much oppose the arc (whatever that might mean) but force the arc to move away from the pole gap, increasing the arc distance faster than you could just by moving the pole pieces apart. The end result is that for DC the arc gets long enough that it can no longer be sustained or for AC the arc gets long enough that it cannot reignite after the zero crossing of the current.
AFAIK the magnetic field is created by coils, so that for AC it can always be of the correct polarity relative to the current direction so that the arc is always moved in the same direction.

Like given

 

[GoldDigger]

A note that can be of importance to Solar PV users: Some DC breakers use permanent magnets to move the arc. But this means that the enhancement to arc suppression only works with one polarity of the current to be interrupted. That is a problem when, depending on the exact fault nature, the fault current to be interrupted can be in either direction. Or when the fault current and the normal current to be interrupted when the breaker is used as a switch are in opposite directions.